Turchinov said the decision had been taken in the face of "threats to the lives and health of our service personnel" and their families.

"The National Defense and Security Council has instructed the Defense Ministry to carry out a re-deployment of military units in Crimea and carry out the evacuation of their families," he said.

Early Monday morning, Russian troops forced their way into a Ukrainian marine base in the Crimean port city of Feodosia, overrunning one of the few symbols of resistance left after Moscow wrestled the peninsula away from Kiev.

The Ukrainian Defense Ministry said Russian troops detained up to 80 Ukrainian servicemen on-site and took two injured Ukrainians away by helicopter.

The Russians used stun grenades and fired automatic weapons as they charged in, a Ukrainian military official said. Ukrainian flags had been taken down from flagpoles inside the base.

Ukrainian army officer, First Lieutenant Anatoly Mozgovoy, told Reuters by phone from inside the compound that the Russians had fired shots and the Ukrainian soldiers were unarmed. Asked if the base had been taken over, he said: "Yes".

"The invading troops were using stun grenades and also firing automatic weapons. The interior of the compound is full of Russian troops," said Vladislav Seleznyov, a Ukrainian military spokesman in Crimea.

Russian forces had already captured part of the base, used by the 1st Separate Marine Battalion, Ukraine's top military unit, earlier this month.

But Ukrainians had previously appeared to be in control of the armory, the barracks and other facilities in the compound.

Russia's seizure of Crimea, a Black Sea peninsula of two million people with a narrow ethnic Russian majority, has been largely bloodless.

Moscow formally annexed Crimea
on March 21 in a move not recognised by Kiev and the West, prompting sanctions on Russia over the Cold War-era style conflict.